TLR4 and mucositis: It has been demonstrated that some immunologic pathways involved in the nickel-induced mucositis and dermatitis, i.e., the inflammatory response via the activation of TLR4 and the infiltration of lymphocytes that secrete Interleukin (IL)-17 and Interferon-gamma (IFN)-γ [25,26], have also been supposed or demonstrated in NCWS [5,7,8,9,27].